84 



Single examples are also listed from Galena, 111., and from Iowa 

 (July), Kansas, and New York. It was taken by Mr. Longley 

 in June. 



The principal characteristics of the nymph are as follows : 

 Nymph (supposition) very similar to G. ><o/r//'^/6' ; median 

 labial lobe rounded but short, lateral lobes similar to those of 

 notatus ; abdomen broader, more lance-shaped ; 9 a little longer 

 than 8, with a very short apical spine above ; lateral spines on 

 6 to 9, the last one blunt, half as long as 10, which is short, cy- 

 lindrical ; appendages and legs similar to to those of iwtutus. 



19. Gomphus plaglaius Selys. 



G.fliriiialis, Walsh (female). 



G. notatus, Hagen, '85, p. 270, No. 25 (nymph). 



G.plagiatus, Hagen, '85, p. 269, No. 24 (nymph). 



This is probably the most abundant gomphid nymph in the 

 larger rivers of Illinois. It may be distinguished from any 

 others herein described by the penultimate (ninth) abdominal 

 segment, with its lateral and basal margins about equal and a 

 rudimentary posterior tooth on the median dorsal line, the 

 other segments being without trace of dorsal hooks or eleva- 

 tions. As already stated under e.denius, it is found about 

 Havana in muddy bottoms where there is current, but not so 

 exclusively in these situations as externus. Mr. Grarman re- 

 ported it as the commonest species in waters associated with 

 the Mississippi at Quincy, and states that it does not breed ex- 

 clusively in running water, presumably basing this statement 

 on the fact that he found it in slough-lakes. These lakes form 

 channels of flow during higher stages of the river, but are more 

 or less completely isolated during low water. Unlike similar 

 waters about Havana, these lakes are but scantily supplied 

 with aquatic vegetation. In our general collection are nymphs 

 from Cairo, 111., where they are probably common, judging from 

 the number taken ; from the Rock River at Colona and Milan ; 

 from the Ohio at Golconda ; and from the Illinois at Pekin. 

 The species did not appear in extensive collections from the 

 Sangamon in Champaign county. The nymphs were not more 



